The overarching objective of this project is to determine whether two fear attenuation techniques from behavioral neuroscience research can be translated to augment exposure therapy for anxiety disorders. Specifically, we will test the techniques of fear retrieval and compound extinction. Conducting a brief fear retrieval trial prior to extinction enhances fear reduction through the reconsolidation update mechanism. Conducting compound extinction, in which multiple feared stimuli are confronted simultaneously, enhances fear reduction through the error-correction mechanism. Study 1 (an analogue study) will test both the singular and interactive effects of fear retrieval and compound extinction for enhancing exposure therapy for specific phobia. Study 1 will use a 2 x 2 design, with fear retrieval (yes or no) and compound extinction (yes or no) as the two between-subjects factors. Participants (N=120) with arachnophobia or ophidiophobia will be randomized to one of four groups: (1) exposure as usual (no augmentation), (2) exposure with fear retrieval, (3) exposure with compound extinction, and (4) exposure with fear retrieval and compound extinction. Behavioral and self-report measures will be used to assess the impact of the fear retrieval and compound extinction augmentations on renewal and spontaneous recovery of fear at post-treatment and one-week follow- up (controlling for baseline fear level). The aim of study 2 is to test the feasibility of integrating the most effective treatment augmentation strategy that emerges from study 1 (fear retrieval and/or compound extinction) into prolonged exposure therapy (PE) for posttraumatic stress disorder (PTSD). To provide a preliminary test comparing the efficacy of PE with augmented PE, we will employ an alternating treatments design40 in which each participant receives both interventions. Participants (N=5) will receive 10 sessions of exposure therapy for PTSD, and will be randomized to one of the two treatment conditions (PE or augmented PE) for each session. PTSD symptoms will be assessed at the start of each, weekly session and one week after the last session. Change in PTSD symptoms from the start of a given session to one week later will provide an assessment of the effectiveness of each session of therapy. Since exposure therapy plays a central role in most manualized treatments for anxiety disorders, findings from these two studies could inform the development of more potent exposure therapies across the full spectrum of anxiety disorders.